Chiron to Seek OK for Surgical Implant / Device designed to deliver drug for treating an AIDS-related eye disease

Carl T. Hall, Chronicle Staff Writer

Published
4:00 am PDT, Thursday, July 6, 1995

Chiron Corp. yesterday said it will seek federal approval to market a new surgical implant for the eye designed to treat a viral infection that often causes blindness in people with AIDS.

Analysts said the tiny device may represent a significant advance in drug-delivery technology, one that could be used for other eye conditions as well. It also could turn into an important new source of revenue for the Emeryville biotechnology company.

"It's potentially a very big deal," said John McCamant, associate editor at Medical Technology Stock Letter in Berkeley. He estimated that the market for the AIDS-related implant could be $100 million a year.

Chiron stock closed yesterday at 65 5/16, up 5/16 on Nasdaq.

CO-DEVELOPING THE IMPLANT

Chiron is co-developing the implant, called Vitrasert, along with Palo Alto-based Roche Bioscience, the unit of drug giant Hoffmann- LaRoche formerly named Syntex.

Chiron's vision-devices unit, based in Southern California, contributed the technology for the implant, which is designed to release a Syntex-developed drug, ganciclovir, directly into the eye.

The idea is to get the drug where it's needed in high concentrations, while avoiding the necessity for repeated infusions. On an outpatient basis, surgeons place the polymer-coated, pebble-size device just beyond the patient's field of vision.

Similar technology could incorporate other drugs for different eye conditions, according to Judy Gordon at Chiron Vision. "This is a platform from which a variety of drugs can be delivered," she said. "We believe it's a major step forward. . . . It's very difficult to deliver drugs to the back of the eye."

LEADING CAUSE OF DEATH

In two sets of clinical tests, the implant significantly delayed onset of the opportunistic viral condition in people with AIDS known as CMV retinitis. The virus is a leading cause of death among AIDS patients, afflicting a number of organs but most often showing up in eye infections and, ultimately, blindness.

There are oral treatments for the same condition. But to ensure that an adequate amount gets to the eye, the dose usually must be dangerously high, risking side effects, such as reducing white- blood cells.

Chiron filed for marketing approval with the U.S. Food and Drug Administration, which has promised expedited review. Unless the FDA finds fault with the application, the implant could be on the market by early next year.

Brenda Lein, director of information and advocacy at Project Inform, a San Francisco organization that provides treatment information to people with AIDS, called the eye implant particularly important from the "quality of life" standpoint.

THEY'RE GOING BLIND

"Not only are people in advanced stages of the (AIDS) disease, but they're going blind as well," she noted.

Another biotech company, Gilead Sciences Inc. in Redwood City, is working on a different drug for CMV retinitis called cidofovir.

By the end of this year, Gilead expects to file for marketing approval for a twice-a-month infusion with cidofovir. It lasts much longer in the body than current treatment with the Roche drug, and therefore requires much less frequent doses.

The company is in early stages of tests where the drug is injected into the eye, a scary-sounding alternative but one that avoids both constant infusions and the risk of surgery.